At first glance, the men and women trolling Walgreens, CVS and Publix stores across South Florida appeared to be run-of-the-mill shoplifters.

But their patterns soon became clear, as they hit one pharmacy after another in succession, day in and day out, swiping pricey diabetes strips, pain killers and heartburn medication, investigators say.

What began as a probe into “boosters” morphed into the discovery of a wide-ranging racket. Prosecutors announced Thursday that they had filed criminal charges against 23 people — including mid-level “fences” who in turn supplied the stolen medications to higher-ups. In some cases, prosecutors said, the goods wound up at cut-rate prices in New York shops owned by the family of one of the organizers.

Miami-Dade State Attorney Katherine Fernandez Rundle called the ring a “massive criminal enterprise” that is believed to have looted over $15 million in stolen goods.

“We’re charging them all, from the bottom to the top,” she said at a press conference, flanked by prosecutors, police officials and representatives from Walgreens, CVS and Publix.

In all, police across Florida arrested 16 of the 23 on charges of grand-theft, money laundering — and racketeering, believed to be the first time state authorities have put together such a complex case involving a retail-theft ring.

In all, police pinpointed 13 boosters, some of whom were given pharmacy “orders” by their organized ring handlers, earning as much as $1,000 a day for the pilfering.

The intensive investigation — which lasted over a year and was dubbed “Operation Over the Counter” — followed the boosters as they swiped the goods, then turned and sold them around to the first tier of fences.

Detectives engaged in extensive surveillance, tracing the stolen medications from the pharmacies to innocuous moving boxes stuffed in the backs of cars.

Covert police surveillance footage showed one of the fences, a blonde named Suzanne Mitchell, 52, transferring boxes of stolen goods into the car of Howard Seth Katz, 47, who owned a warehouse in Miramar.

Some of the medications and goods were sent to stores operated by Katz’s family in New York, where they were sold to customers at cut-rate prices, while some were sold online or to wholesale distributors, Fernandez Rundle said.

Katz always paid his fences in checks — copies of which were easily obtained by investigators, according to a warrant by Miami-Dade Detective Miguel Garcia and prosecutor Helen Page Schwartz.

In turn, Katz sold much of his goods, some in meetings in gas station parking lots, to Abel Salek, of Pafco Distributors, and David Cohen, of the company Port Lyn.

None of those charged, or their attorneys, could be reached on Thursday.